1. Field of the Invention
Embodiments of the invention relate to a device and a method for recognizing electromagnetic fields, specifically those fields that occur in image-guided nuclear spin tomography or magnetic resonance tomography devices. (“MRT” or “MRI” stand for magnetic resonance tomography and magnetic resonance imaging respectively, wherein these two acronyms are used interchangeably herein).
2. Description of the Related Art
Although MRI examinations are becoming increasingly important in diagnostic medicine, some patients are contraindicated for MRI examinations. Such a contraindication can be the result of an at least partially implanted medical device (hereinafter also implant or IMD).
To make MRI examinations possible in spite of that, various methods are known that relate either to the performance of the MRI examination or to the implantable medical device.
Among others, technologies for the recognition of magnetic fields are known that are based on conventional methods of magnetic field detection. Thus, US 2008/0154342, describes a method using a GMR sensor (Giant Magnetic Resistance), in order to recognize problematic magnetic fields of MRT devices. However, these technical approaches are not very specific and generate an increased energy requirement, which leads to a shorter service life at the same energy reserves.
Systems are also known in prior art that use the change of vibration parameters for the determination of changes of the strength of magnetic fields for periodically vibrating systems, as is described in US 2006/0265139. Because of the general conditions, such as, for example, the periodic vibration, such systems are not suitable for the detection of magnetic fields in the area of implants.